Thiol–thione tautomeric forms recognition on the example of 4‐[3‐(2‐methyl‐furan‐3‐yl)‐5‐thioxo‐1,2,4‐triazolin‐4‐yl]acetic acid

The synthesis of 4‐3‐(2‐methyl‐furan‐3‐yl)‐5‐thioxo‐1,2,4‐triazolin‐4‐yl]acetic acid, its structural study in the solid state, and the thiol–thione tautomeric recognition on the basis of spectroscopic data and theoretical calculations are presented. It is shown that NMR spectra, especially ¹³C and ¹⁵N, are indicative of the actual tautomeric form whereas vibrational data can be ambiguous. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:337–344, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20433